<?php
  header('Content-Type: application/json;charset=utf-8');
  header('Access-Control-Allow-Origin:*'); // *代表允许任何网址请求
  header('Access-Control-Allow-Methods:POST,GET,OPTIONS,DELETE'); // 允许请求的类型
  header('Access-Control-Allow-Credentials: true'); // 设置是否允许发送 cookies
  header('Access-Control-Allow-Headers: Content-Type,Content-Length,Accept-Encoding,X-Requested-with, Origin'); // 设置允许自定义请求头的字段

  require_once("conn.php");

  $username = $_POST['username'];
  $password = $_POST['password'];
  $role = $_POST['role'];

  $sql = "select `user_id` from `user` where `user_username`='$username' and `user_password`='$password' and `user_role`='$role'";

  $query=mysqli_query($conn, $sql);
  $res = mysqli_num_rows($query);
  if($res) {
    echo "success";
  }else {
    echo "failed";
  }
?>